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Birds of a feather breed together

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28.04.2005

A study at the University of Sheffield, and published in Nature on Thursday 28 April 2005, has found that long-tailed tits rely on a family support network to bring up their offspring, and that they recognise family members through an individual family call that they learn in the nest.

Long-tailed tits breed co-operatively, with ‘helpers’ working together with breeding pairs to increase the chance that young are reared successfully to adulthood. These helpers choose to help chicks that are closely related to them. In this way they benefit by helping chicks that are genetically close to them to survive.

The study first showed that individuals recognise their kin from their calls. It was then established that a brood of young all learn similar calls from their relatives, so kin sound more alike than non-kin.

Stuart Sharp, of the Department of Animal and Plant Sciences at the University of Sheffield, and lead author, explains, “We began by trying to establish that the birds differentiate between individuals using calls. We hypothesised that the long-tailed tit’s ‘churr’ call may be the one they use to recognise kin, as this is a common contact call.

“We observed the responses of birds when we played them the calls of a related and unrelated bird, and then the same calls but slightly manipulated. We found that the responses of birds to the non-manipulated calls of their relatives was different to their responses to all of the other calls. This demonstrated that the birds were hearing something in the call of their relative that established kinship.

We then focussed on how this call is acquired - whether it is genetically determined or learnt during development. By fostering chicks with relatives and non-relatives and subsequently recording their calls when they reached adulthood, we showed that chicks learn the ‘churr’ from the adults who care for them.”

Lorna Branton | Source: alphagalileo
Further information: www.shef.ac.uk

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